1. Field of the Invention
The present invention relates to rail pads, and particularly to a pad which is positioned between the foot of a railway rail and an underlying rail foundation on which the rail stands, in order to cushion the rail from the foundation, so as to limit the transmission of dynamic forces to the foundation. The pad also insulates the rail electrically from the foundation if it is required to pass electric currents through the rail, for example for signalling work.
2. Description of the Prior Art
In some cases such a pad comprises a membrane of elastomeric material, for example natural rubber, with protrusions extending in opposite directions from its two major faces: see, for example, United Kingdom Patent Specifications Nos. 841776 and 2161524. The protrusions may, for example, be in the form of cylindrical studs or ribs running along and/or across the pad.
In some pads, for example as disclosed in United Kingdom Patent Specification No. 611753, U.S.S.R. Patent Specification No. 180437, and German Patent Specification No. 2504165, the protrusions on one face of the pad do not register, i.e. overlap, with those on the opposite face so that when the membrane is horizontal no vertical line through the pad passes through more than one protrusion. It is believed, however, that none of these pads have been used, or proposed for use, in a rail/rail foundation assembly.